Can my MacBook use 40MHz bandwidth?

[zjohnr]

At this point in time I have an extremely simple wireless LAN. It consists of a DIR-655 (Rev A4, v1.21) and a MacBook (early 2008, MB403LL/A).

I currently have the DIR-655 set to use 40MHz bandwidth. I was wondering if there is any way to tell if this actually is buying me anything or not? I understand from reading other forum posts that not all clients will support a 40MHz channel. I think that the adapter used by my MacBook is one of them, but would like additional confirmation of this, if it's possible.

The only information I seem to be able to find in the web interface to the DIR-655 is the following status info:

Wireless LAN

Wireless Radio : Enabled
802.11 Mode : 802.11n only
Channel Width : 40MHz
Channel : 11
Secondary Channel : 7​

​

The only info I know about what the MacBook client uses for wireless follows below. I'm assuming that since the "secondary" channel 7 is not mentioned, it probably is not used.

AirPort Card Information:

Wireless Card Type: AirPort Extreme (0x14E4, 0x88)
Wireless Card Locale: USA
Wireless Card Firmware Version: Broadcom BCM43xx 1.0 (5.10.38.35)
Current Wireless Network: MonkeyGateN
Wireless Channel: 11​

​

I was wondering if anyone could point me toward a way to learn more about what's going on "under the covers" than what I've got so far. Granted, I don't really need to know this. But I'm curious.

-irrational john

 

[thiggins]

All you have to do is set the router to 40 MHz mode and see if the client connects. If it does, see what link rate it reports.

If the link rate is > 130 Mbps, then the client is connecting with a 40 MHz bandwidth.

Using 40 MHz bandwidth can buy you more throughput under strong signal conditions. But it reduces your effective range. It also eats up twice the bandwidth, so is not a neighbor-friendly mode.

 

[zjohnr]

All you have to do is set the router to 40 MHz mode and see if the client connects. If it does, see what link rate it reports.

If the link rate is > 130 Mbps, then the client is connecting with a 40 MHz bandwidth.

Thanks, Tim. The only way I know of to display the link rate for my wireless connection is to use the Status tab of my DIR-655's web configuration. The max I've ever seen it show is 130 Mbps, never more.

So it would seem that setting the DIR-655 channel width to 40MHz doesn't yield any better throughput with my early 2008 MacBook. Guess I may as well leave it at 20MHz ...

Which makes ponder the 802.11n Zen question of, "If support for a feature is not implemented but no one notices, is it really missing?"

I guess the answer from a marketing point of view is, "Nope".

Using 40 MHz bandwidth can buy you more throughput under strong signal conditions. But it reduces your effective range. It also eats up twice the bandwidth, so is not a neighbor-friendly mode.

The nearest wireless network I know of is in the neighbor's house, maybe 80 feet from my router. That network is an 802.11g with WEP on channel 6. I don't think I'm any threat to them since my DIR-655's signal has to be quite attenuated over there and I'm always on channel 11 (it seems).

The only other nearby hotspot I'm aware of is an 802.11b open network on channel 14 (??). That's from a motel which is across the highway from me. Maybe 200 feet? The SSID shows up. Even though it's "open", I've never been able to connect to it. Not that I care much ... only my geekish curiosity to see if it would even work.

I thought the only 2.4 MHz wireless channels used were 1 to 11? Why would my hotspot detector show channel 14 for the motel's wireless? Strange.

-irrational john

 

[thiggins]

You need to look at the client's (the MacBook) link rate, not the router. I just looked at my DIR-655, which has a client associated that is reporting a 117 Mbps link rate, while the 655's wireless status says 39 Mbps...

Channel 14 is allowed in Japan, so some routers can be set to use that Frequency, although it's supposed to not be used. Anyway, your motel neighbor is thinking that he is getting a clear channel by using 14.

In truth, he's just setting himself up for being interfered with by Channel 11 users, since his signal on Channel 14 will just look like noise and the normal bandwidth sharing mechanisms built into 802.11 won't work.

 

[zjohnr]

You need to look at the client's (the MacBook) link rate, not the router.

I would if I knew how to do this. But I have not been able to figure out how to display the link rate in OS X 10.5 on my MacBook.

I suppose I could reinstall Boot Camp and then see what windows shows me ... <sigh>

-irrational john

 

[thiggins]

I would if I knew how to do this. But I have not been able to figure out how to display the link rate in OS X 10.5 on my MacBook.

http://discussions.apple.com/thread.jspa?messageID=6623194

 

[zjohnr]

Thanks again, Tim.

The AP Scanner app also reports 130 Mbps as the link rate whether the DIR-655 is set to 20MHz or 40MHz. So I'm thinking unless someone else disputes this, I'll call it that the early 2008 MacBook series only supports 20MHz as a wireless N client.

Pity. But I suppose not that surprising.

-irrational john

 

[zjohnr]

Possible reason why no 40MHz (in 2.4 GHz?) in MacBook

While basically just glancing at some older Apple Airport/wireless links I came across some comments in the article below that may pertain.
Apple Ships 802.11n Base Station, Software Upgrade, January 30, 2007 at Wi-Fi Networking News

In 2.4 GHz, Apple won't allow 40 MHz "wide" channels that, in the absence of other Wi-Fi network signals, could double throughput. Moody explained that Apple has a huge interest in preserving the functionality of Bluetooth, which has shipped alongside Wi-Fi in most Macs in recent years. "We need to make sure Bluetooth and [802.11]g co-exist perfectly," he said. Allowing 40 MHz wide channels in 2.4 GHz would have severely constrained Bluetooth. Starting with version 1.2 of Bluetooth, that short-range networking standard actively avoids frequencies that are in use by Wi-Fi. ​

Now obviously the comments above are about the 2007 Airport Extreme, not (my) 2008 white MacBook. Also, the final sentence implies (to me) that with the current versions of Bluetooth there should be no need avoiding 40 MHz in 2.4 GHz.

But maybe it still applies? It wouldn't surprise me at all if some limitation was put into the clients as well as the routers for the reasons above. And then they ... what? ... just "forgot about it".

-irrational john

 

[Larsalex]

MacBook Pro & DIR-655

So yeah, I'm wondering the same. Does the macbook pro (also early 2008) support 40MHz.

Just bought a DIR-655 A4 1.21EU firmware. Had some weird issues while setting it up. Every time after making changes to wireless settings to the DIR-655, the DIR-655 reboots and the wireless connection is obviously gone. But after that macbook would not reconnect by itself. I had to select the wirless network again. And after that, the speed went down from about 58 Mbps to 13 or even 1 Mbps. This with a signal strength of 50 - 60%!?
Took me a while to figure out I had to reboot the Mac in fact to get the 58 Mbps again... No idea why. Not very convenient to have to reboot after every wireless settings change.

Anyway, the Dlink reports 40MHz connection. Though speeds are never above 130Mbps (placed the router now very close to have a near 100% strength). Which judging from reports here means that it uses 20MHz, right?

Have not found a way to verify on the macbook.

Great site this by the way. Extremely helpful.

Lars

 

[thiggins]

What counts is the rate that the client (MacBook) reports. Since Apple doesn't make it easy to get that info, you need to use the link up in Post #6 in this thread to get the link rate.

But as far as I know, Apple still locks out using 40 MHz bandwidth mode in 2.4 GHz. If 130 Mbps is the highest link rate you see, then you're limited to 20 MHz bandwidth.

Truthfully, you're not missing much by being limited to 20 MHz bandwidth. It really only provides a throughput boost under strong to medium signal conditions and actually reduces your range, i.e. won't connect reliably with low strength signals.

 

[Larsalex]

Return for 825?

Thanks for the reply.

Since I can still return the 655 I'm wondering if it makes sense to replace it by an 825. I was almost to buy the 825. Reason for this is it would give me a 5GHz option and would also give me one less antenna. And then the 825 is quite a bit more expensive. But, there are lots of WiFi networks here (on avarage about 16).

I don't even know if the macbook will do 5GHz. I think it is available when using Apple routers. But will it also work with other brands?
And then there is the reduction in range. I wonder if the two vs three antenna setup will limit range on its own. If combined with 5GHz this could mean a serious drop in range.

I now have the router placed in the living room. But I would like to place it next to the fusebox, which at the moment gives me 50% strength when DIR-655 placed there. And speeds are hovering around 40 - 78Mbps.

The question is also how much do neighboring WiFi networks interfere? I don't think netstumbler tools show 5GHz networks judging from the channels. I do manage to find a free channel (13 or 4 mostly) but would the step to 5GHz give a boost even with lower signal strength because there is less interference?

Too bad there's no option to rent routers so you can try-before-you-buy all of them.

 

[thiggins]

Your MacBook will support 5 GHz. Apple moved to dual-band draft 11n across their product line some time ago.

Two vs. three antennas isn't a range issue. The third antenna is for receive only and can increase speed in some cases.

The main issue with 5 GHz is that the signal is attenuated more when passing through obstacles like walls and ceilings. Since you are getting about 50% strength in 2.4 GHz, my guess is that you would get a 5 GHz signal. But your speed could be slower.

2.4 GHz networks won't interfere with the 5 GHz signal. Chances are there are very few if any 5 GHz networks around (if you are not in Japan, at least).

You might consider the Linksys WRT400N instead of the DIR-825.

 

[occamsrazor]

Sorry to raise this thread from the dead.... I have an Early 2009 MacBook Pro with the following wireless card:

Card Type: AirPort Extreme (0x14E4, 0x8D)
Firmware Version: Broadcom BCM43xx 1.0 (5.10.91.27)

From above in this thread, it's indicated that Apple "locks out using 40 MHz bandwidth mode in 2.4 GHz"...

Is this the case for all Apple Airport (internal) cards?

Does this mean that you *can* use 40Mhz channels in 5Ghz?

Thanks...

 

[zjohnr]

I doubt it ...

From above in this thread, it's indicated that Apple "locks out using 40 MHz bandwidth mode in 2.4 GHz"...
Is this the case for all Apple Airport (internal) cards?

I wouldn't be at all surprised if Apple still does not support 40 MHz. Apple appears to only push the hardware when/if it suits them. And since effectively no one knows about this I would guess Apple has no reason to make any changes.

FWIW, The system profiler provides more information now under Snow Leopard. It appears to now give the link rate (see excerpt below). If you're running Snow Leopard you could look and see if you're getting anything better than 130 Mbps.

-irrational john

Card Type: AirPort Extreme (0x14E4, 0x88)
Firmware Version: Broadcom BCM43xx 1.0 (5.10.91.27)
Locale: FCC
Country Code: US
Supported PHY Modes: 802.11 a/b/g/n
Supported Channels: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 36, 40, 44, 48, 52, 56, 60, 64, 149, 153, 157, 161, 165
Wake On Wireless: Supported
Status: Connected

Current Network Information:
MonkeyGateN:
PHY Mode: 802.11n
BSSID: 0:22:b0:c7:c3:a1
Channel: 11
Network Type: Infrastructure
Security: WPA2 Personal
Signal / Noise: -54 dBm / -91 dBm
Transmit Rate: 130
MCS Index: 15

Other Local Wireless Networks:
Clarity_Connect_Embassy_Inn:
PHY Mode: 802.11g
BSSID: 0:21:29:68:40:dd
Channel: 6
Network Type: Infrastructure
Security: None
Signal / Noise: -76 dBm / -93 dBm
nanbrownathome:
PHY Mode: 802.11g
BSSID: 0:18:f8:fb:21:e7
Channel: 6
Network Type: Infrastructure
Security: WEP
Signal / Noise: -82 dBm / -93 dBm

 

[occamsrazor]

I wouldn't be at all surprised if Apple still does not support 40 MHz. Apple appears to only push the hardware when/if it suits them. And since effectively no one knows about this I would guess Apple has no reason to make any changes.
FWIW, The system profiler provides more information now under Snow Leopard. It appears to now give the link rate (see excerpt below). If you're running Snow Leopard you could look and see if you're getting anything better than 130 Mbps.
-irrational john

What router is that N network you're showing - and is it in 5Ghz / 40mhz mode?
I don't yet have an N wireless router yet, I'm asking the questions to see how much it's worth me upgrading, and what device I should get... If Apple isn't supporting 40Mhz channels in their laptop cards, there's not much point me getting a router that does...

 

[thiggins]

As far as I know, Apple still does not allow 40 MHz bandwidth mode, i.e. link rates above 130 Mbps, in the 2.4 GHz band. They do allow 40 MHz bandwidth in the 5 GHz band.

 

[zjohnr]

D-Link DIR-655

What router is that N network you're showing - and is it in 5Ghz / 40mhz mode?

It's a D-Link DIR-655 which does not support 5GHz, only 2.4GHz. I've been happy enough with it so far, but as a design, it is getting rather long in the tooth at this point. One of the reasons I went with it anyway is that D-Link has so far been supplying updates to the firmware. (Probably simply because the router itself has turned out to be so popular).

Nothing I hate more than buying a product which can arguably be "made better" through firmware updates only to find that the manufacturer has decided to cut their losses and abandon all but token support for the product.

I can understand why it makes sense to them to do this. However, that doesn't make me any less irritated or frustrated. But I digress ...

If Apple isn't supporting 40Mhz channels in their laptop cards, there's not much point me getting a router that does...

To my knowledge it's rare to find a wireless N router that would not support 40 MHz bandwidth. My guess ... and it's only a guess ... is that the cheapest (single stream??) 802.11n routers might not. Most likely Apple also doesn't bother to provide support in their Airport routers either. After all, Apple knows best all the time in all cases, no?

-irrational john

 

[occamsrazor]

So to sum up, if you're using an Apple airport card... Apple will prevent using 40Mhz bandwidth on 2.4Ghz, you need a router running at 5Ghz to take advantage of 40Mhz. That's useful, thanks all....

 

[thiggins]

So to sum up, if you're using an Apple airport card... Apple will prevent using 40Mhz bandwidth on 2.4Ghz, you need a router running at 5Ghz to take advantage of 40Mhz. That's useful, thanks all....

Incorrect. Apple routers support only 20 MHz bandwidth mode in the 2.4 GHz band for all clients, not just apple.

 

[occamsrazor]

Incorrect. Apple routers support only 20 MHz bandwidth mode in the 2.4 GHz band for all clients, not just apple.

OK, fair enough, I was talking about something else though. You were referring to this situation:

1. Any card > Apple Router: 2.4Ghz/40Mhz impossible, 5Ghz/40Mhz possible (assuming Apple router is one that does 5Ghz)

I was talking about this situation:

2. Apple card > Non-Apple Router: ???

I guess my point... or question is... does Apple prevent an Apple card from connecting to a 3rd Party router at 2.4Ghz/40Mhz? Because if so then owners of Apple cards would need a router (Apple or Other) that runs at 5Ghz to take advantage of 40Mhz bandwidth....